Process considerations of a biorefinery producing value-added products from corn fibre

Corn fibre, a co-product of corn wet milling, can be a suitable raw material of a biorefinery producing biofuels and value-added chemicals. The simulated process is able to produce bioethanol, biomethane and xylitol synergistically, while it also covers its own heat demand. The proposed plant consists of the following process steps: fractionation, enzymatic hydrolysis and ethanol fermentation, distillation and dehydration, anaerobic digestion, biogas upgrading, aerobic waste water treatment, combined heat and power production, xylitol fermentation and recovery. Various scenarios of the biorefinery were investigated and the process configurations were compared in terms of energy efficiency, or mass flows of the products. Incineration of the sludge and production of district heat are found to be effective methods to increase the energy efficiency, on which aerobic sludge yield has a great effect. The solid-liquid separations, which are carried out in filterpress, have a curial role in terms of energy efficiency. Combustion of the solid part of cellulose hydrolysis residue is favourable compared with the anaerobic digestion, except if the dry matter content of the filterpressed solid was set to 30% instead of 40%. The amounts of the produced xylitol and biomethane are variable, which ensures the ability of market adaptation for the biorefinery.